Electrolytic capacitor, method for manufacturing same, and electrolytic capacitor module

ABSTRACT

An electrolytic capacitor includes a capacitor element and a liquid component. The capacitor element includes an anode body that includes a dielectric layer on a surface of the anode body and a conductive polymer that covers a part of the dielectric layer. The liquid component includes a first solvent and a polyalkylene glycol component. The first solvent contains at least a glycerin component.

BACKGROUND 1. Technical Field

The present disclosure relates to an electrolytic capacitor, a methodfor manufacturing the electrolytic capacitor, and an electrolyticcapacitor module.

2. Description of the Related Art

As a small-sized, large-capacitance capacitor having a low equivalentseries resistance (ESR), a promising candidate is considered to be anelectrolytic capacitor including an anode body having a dielectric layerformed thereon, a conductive polymer covering at least a part of thedielectric layer, and an electrolytic solution. As the electrolyticsolution, a liquid component such as a non-aqueous solvent or a solutionobtained by dissolving a solute in a non-aqueous solvent is used.

Unexamined Japanese Patent Publication No. 2019-71469 has proposed anelectrolytic capacitor including: a capacitor element that includes ananode body having a dielectric layer formed thereon, a conductivepolymer that covers at least a part of a surface of the dielectriclayer, and an electrolytic solution including an non-aqueous solvent, aglycerin compound, and an ionic solute. In the electrolytic capacitor,the mass of the glycerin compound included in the electrolytic solutionis in a range of 2 to 100 times the mass of the conductive polymerattached to the capacitor element.

Japanese Patent No. 6535409 has proposed the following manufacturingmethod of a solid electrolytic capacitor. The manufacturing methodincludes: a first introduction step of introducing a dispersion liquidincluding a particulate conductive polymer compound and a firstwater-soluble compound into a capacitor element; and a secondintroduction step of introducing a water-soluble polymer solutionincluding liquid polyethylene glycol, water, and a second water-solublecompound so as to surround a solid electrolyte layer formed in the firstintroduction step. A water-soluble polymer solution not including aparticulate conductive polymer compound is used in the secondintroduction step, and the same substance as the first water-solublecompound is used as the second water-soluble compound. The firstwater-soluble compound is diglycerin, a compound having a molecularweight of 100 or more and less than 200 and four or more hydroxylgroups, or both thereof.

Unexamined Japanese Patent Publication No. 2018-110232 has proposed thatan electrolytic solution including a polyglycerin derivative is used ina solid electrolytic capacitor.

Unexamined Japanese Patent Publication No. 2017-69549 has proposed thatan electrolytic solution including an adduct of alkylene oxide to a tri-to octahydric polyhydric alcohol is used for a hybrid type electrolyticcapacitor.

Unexamined Japanese Patent Publication No. 2016-72284 has proposed asolid electrolytic capacitor in which a solvent containingpolyoxyethylene glycerin or a derivative thereof is filled in voids of acapacitor element.

SUMMARY

An electrolytic capacitor according to a first aspect of the presentdisclosure includes a capacitor element and a liquid component. Thecapacitor element includes an anode body that includes a dielectriclayer on a surface of the anode body, and a conductive polymer thatcovers a part of the dielectric layer. The liquid component includes afirst solvent and a polyalkylene glycol component. And the first solventcontains at least a glycerin component.

An electrolytic capacitor according to a second aspect of the presentdisclosure includes a capacitor element and a liquid component. Thecapacitor element includes an anode body that includes a dielectriclayer on a surface of the anode body, a cathode body, and a conductivepolymer that is disposed between the anode body and the cathode body.The liquid component includes a first solvent and a polyalkylene glycolcomponent. And a solubility parameter of the first solvent is 15(cal/cm³)^(1/2) or more.

An electrolytic capacitor module according to a third aspect of thepresent disclosure includes a plurality of electrolytic capacitors whichare connected in parallel. The plurality of electrolytic capacitorsincludes the above-described electrolytic capacitor.

A method for manufacturing an electrolytic capacitor according to afourth aspect of the present disclosure is a method for manufacturing anelectrolytic capacitor including a capacitor element and a liquidcomponent. The capacitor element includes an anode body including (i) adielectric layer on a surface of the anode body and (ii) a conductivepolymer covering a part of the dielectric layer. The method includes: astep of preparing a liquid component that includes a first solventcontaining at least a glycerin component, and a polyalkylene glycolcomponent; a conductive polymer impregnating step of impregnating thedielectric layer with the conductive polymer; and a liquid componentimpregnating step of impregnating the capacitor element with the liquidcomponent after the conductive polymer impregnating step.

A method for manufacturing an electrolytic capacitor according to afifth aspect of the present disclosure is a method for manufacturing anelectrolytic capacitor including a capacitor element and a liquidcomponent. The capacitor element includes an anode body including (i) adielectric layer on a surface of the anode body and (ii) a conductivepolymer covering a part of the dielectric layer. The method including: astep of preparing a liquid component that includes a first solventhaving a solubility parameter of 15 (cal/cm³)^(1/2) or more, and apolyalkylene glycol component; a conductive polymer impregnating step ofimpregnating the dielectric layer with the conductive polymer; and aliquid component impregnating step of impregnating the capacitor elementwith the liquid component after the conductive polymer impregnatingstep.

An electrolytic capacitor and an electrolytic capacitor module that areexcellent in heat resistance can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view illustrating an electrolyticcapacitor according to an exemplary embodiment of the presentdisclosure; and

FIG. 2 is a schematic view illustrating a partially developed capacitorelement of the electrolytic capacitor of FIG. 1.

DETAILED DESCRIPTIONS OF EMBODIMENT

An electrolytic capacitor may be used in a high-temperature environmentdepending on use applications, and thus high heat resistance isrequired.

When an electrolytic capacitor that includes a liquid componentincluding a non-aqueous solvent is used in a high-temperatureenvironment, the non-aqueous solvent is likely to evaporate, andsufficient durability is difficult to obtain. Thus, it is preferable touse a liquid component including a non-aqueous solvent having arelatively high boiling point. However, when the boiling point of thenon-aqueous solvent is high, the viscosity of the liquid component mayincrease, and thus it may be difficult to impregnate the capacitorelement with the liquid component. When such a non-aqueous solvent isused, dissociability of the solute may decrease, and thus it may bedifficult to secure the characteristics of the electrolytic capacitor.When the length of linked carbon atoms in the molecular chain of thenon-aqueous solvent increases, the affinity with an elastic polymercontained in a sealing body increases, and thus the sealing body iseasily swollen by the non-aqueous solvent. When the electrolyticcapacitor in which the sealing body is swollen by the non-aqueoussolvent is exposed to a high-temperature environment, deterioration ofthe sealing body progresses, and durability decreases. In the relatedart, various non-aqueous solvents have been mentioned as the non-aqueoussolvent used for the liquid component of the electrolytic capacitor, butit is very difficult to obtain a liquid component excellent in thebalance of characteristics as described above.

In an electrolytic capacitor of an aspect of the present disclosure, aliquid component including a first solvent and a polyalkylene glycolcomponent is used in an electrolytic capacitor that includes a capacitorelement including a conductive polymer. The first solvent satisfies atleast one of the following conditions (a) and (b).

(a) The first solvent contains at least a glycerin component.

(b) The solubility parameter (SP value) of the first solvent is 15(cal/cm³)^(1/2) or more.

Although such a first solvent tends to exhibit relatively highhydrophilicity, it is difficult to actually use for the liquid componentof the electrolytic capacitor because it has low solubility to anon-aqueous solvent. However, when such a first solvent is used incombination with the polyalkylene glycol component, the first solvent iseasily dissolved, the viscosity of the liquid component can berelatively low, and thus high dissociability of the solute can besecured. Hence, the first solvent can be used as the liquid component ofthe electrolytic capacitor. Since such a liquid component includes thefirst solvent, it is difficult for the liquid component to volatilizeeven in a high-temperature environment, and since the affinity of thefirst solvent for the elastic polymer contained in the sealing body islow, the liquid component hardly swells the sealing body. Thus, highheat resistance of the electrolytic capacitor can be secured. Since theglycerin component easily enhances the orientation of the conductivepolymer included in the capacitor element, the conductivity of theconductive polymer can be enhanced.

Hereinafter, the configuration of the electrolytic capacitor and amethod for manufacturing the electrolytic capacitor will be described inmore detail.

[Electrolytic Capacitor]

The electrolytic capacitor includes a capacitor element and a liquidcomponent. The electrolytic capacitor usually includes a container thathouses the capacitor element and the liquid component and a sealing bodythat seals the container.

(Liquid Component)

The liquid component may include one or two or more kinds of firstsolvents.

(First Solvent)

In the above condition (a), the first solvent contains at least aglycerin component. The first solvent can contain a solvent having an SPvalue of 15 (cal/cm³)^(1/2) or more, in addition to the glycerincomponent. From the viewpoint of securing the effect of the glycerincomponent, the proportion of the glycerin component in the first solventmay be 90 mass % or more. The first solvent may contain only theglycerin component.

In general, when a component having a large amount of hydroxy groups isused as the liquid component, the liquid component easily permeates thesealing body. Meanwhile, when the glycerin component is used, a largeamount of the glycerin component remains in the liquid component even ina high-temperature environment, so that high orientation of theconductive polymer can be maintained in the high-temperatureenvironment.

Examples of the glycerin component include glycerin or a derivativethereof, and polyglycerin or a derivative thereof. The liquid componentmay include one kind of glycerin component, or may include two or morekinds of glycerin components.

The polyglycerin includes a repeated structure of a glycerin unit. Thenumber of repetitions of glycerin units included in polyglycerin ranges,for example, from 2 to 20, inclusive, and may range from 2 to 12,inclusive, or 2 or more and less than 12, or may range from 2 to 10,inclusive, or from 2 to 6, inclusive. The polyglycerin is alsopreferably diglycerin, triglycerine, or the like.

Examples of the derivative of glycerin or polyglycerin include an esterin which at least a part of hydroxy groups of glycerin or polyglycerinis esterified, and an alkylene oxide adduct of glycerin or polyglycerin.Examples of the ester include organic acid esters (such as acetic acidester). More specific examples of the alkylene oxide adduct include anadduct in which one molecule of alkylene oxide is added to one hydroxygroup for at least a part of hydroxy groups. Examples of the alkyleneoxide include C₂₋₄ alkylene oxide, and C₂₋₃ alkylene oxide or ethyleneoxide is preferred. When the alkylene oxide adduct includes a pluralityof alkylene oxide units, at least two alkylene oxide units may be of thesame type, or all the alkylene oxide units may be of different type.

The number of hydroxy groups of the derivative is not particularlylimited. The derivative may not have a hydroxy group. The number ofhydroxy groups of the derivative may range, for example, from 0 to 10,from 0 to 8, from 1 to 8, or from 2 to 8.

From the viewpoint of easily orienting the conductive polymer, it ispreferable to use a glycerin component having a hydroxy group at each ofat least two carbon atoms adjacent to each other. The derivative ispreferably an alkylene oxide adduct. These glycerin components easilyswell the conductive polymer and easily orient the conductive polymer.Hence, the film restoration effect of the dielectric layer can beenhanced, and the ESR can be reduced.

In the above condition (b), specific examples of the first solventhaving an SP value of 15 (cal/cm³)^(1/2) or more include theabove-described glycerin components. Among the glycerin components,glycerin or an alkylene oxide adduct thereof, and polyglycerin having anumber of repetitions of glycerin units of from 2 to 12, inclusive (from2 to 10, inclusive) or an alkylene oxide adduct thereof are preferred.The first solvent may contain one or two or more kinds of solventshaving an SP value of 15 (cal/cm³)^(1/2). The SP value is, for example,22 (cal/cm³)^(1/2) or less, and may be 20 (cal/cm³)^(1/2) or less. Thefirst solvent having an SP value of 15 (cal/cm³)^(1/2) or more ispreferably an organic solvent. Note that, it is established that 1(cal/cm³)^(1/2) ≃2.05 (J/cm³)^(1/2) ≃2.05 (MPa)^(1/2).

The content proportion of the first solvent in the liquid component is,for example, 5 mass % or more, preferably 10 mass % or more, and morepreferably more than 10 mass %, and may be 15 mass % or more, 20 mass %or more, 25 mass % or more, or 30 mass % or more. When the contentproportion of the first solvent is in such a range, the conductivepolymer is likely to swell. When content ratios of the other componentsare relatively decreased, the effect of suppressing swelling of thesealing body due to the liquid component is enhanced. The contentproportion of the first solvent in the liquid component may be 95 mass %or less, and is preferably 90 mass % or less, and more preferably 75mass % or less or 70 mass % or less. When the content proportion of thefirst solvent is in such a range, the viscosity of the liquid componentcan be low, and thus high dissociability of the solute is easilysecured. These lower and upper limit values of the range in the contentproportion of the first solvent can be arbitrarily combined.

(Polyalkylene Glycol Component)

The polyalkylene glycol component may be any component having a repeatedstructure of alkylene oxide. Examples of the alkylene oxide include C₂₋₄alkylene oxide, and the alkylene oxide may be C₂₋₃ alkylene oxide.Specific examples of the alkylene oxide include ethylene oxide,propylene oxide, trimethylene oxide, and butylene oxide. Thepolyalkylene glycol component may include one kind of alkylene oxideunit or may include two or more kinds of alkylene oxide units. Thepolyalkylene glycol component including two or more kinds of alkyleneoxide units may include, for example, an ethylene oxide unit and a C₃₋₄alkylene oxide unit. When the polyalkylene glycol component includingtwo or more kinds of alkylene oxide units is used, the effect ofreducing the viscosity of the liquid component is enhanced.

Examples of the polyalkylene glycol component include polyalkyleneglycol, a copolymer including two or more kinds of alkylene oxide units,and a polyalkylene oxide adduct of a polyhydric alcohol. Examples of thepolyhydric alcohol include glycerin, trimethylolpropane, and sugaralcohols. Examples of the sugar alcohol include sugar alcohols havingfour or more hydroxy groups (such as monosaccharide alcohol anddisaccharide alcohol). Examples of the sugar alcohol include sorbitol,mannitol, erythritol, pentaerythritol, threitol, arabinitol, ribitol,xylitol, galactitol, rhamnitol, isomaltose, maltitol, lactitol,palatinose, and reductants thereof (for example, reduced palatinose). Inthe polyalkylene oxide adduct, two or more polyalkylene oxide chains maybe the same polyalkylene oxide chain, or all the polyalkylene oxidechains may be different.

The liquid component may include one kind of polyalkylene glycolcomponent, or may include two or more kinds of polyalkylene glycolcomponents.

The weight average molecular weight (Mw) of the polyalkylene glycolcomponent is, for example, 150 or more, and preferably 200 or more. Whenthe Mw is in such a range, the first solvent is easily dissolved, andthe viscosity of the liquid component can be low although the liquidcomponent includes the first solvent. The effect of suppressingvolatilization of the liquid component can be enhanced. The Mw is, forexample, 3000 or less, and may be 2000 or less or 1000 or less, or maybe 800 or less or 600 or less. When the Mw is in such a range, theviscosity of the liquid component can be further suppressed. These lowerand upper limit values of the range in the Mw of the polyalkylene glycolcomponent can be arbitrarily combined.

In the present specification, a weight average molecular weight (Mw) isa value in terms of polystyrene as measured by gel permeationchromatography (GPC). Usually, GPC is measured using a polystyrene gelcolumn and water/methanol (volume ratio: 8/2) that form a mobile phase.

The content proportion of the polyalkylene glycol component in theliquid component is, for example, 5 mass % or more, and may be 10 mass %or more, 25 mass % or more, 30 mass % or more, or 50 mass % or more. Inthis case, the solubility of the first solvent can be enhanced, and theviscosity of the liquid component can be low even though the liquidcomponent includes the first solvent. The content proportion of thepolyalkylene glycol component in the liquid component is, for example,95 mass % or less, and may be 90 mass % or less, less than 90 mass %, 80mass % or less, 75 mass % or less, 70 mass % or less, or 50 mass % orless. In this case, even when the electrolytic capacitor is used in ahigh-temperature environment, swelling of the sealing body due to theliquid component can be more effectively suppressed. These lower andupper limit values of the range in the content proportion of thepolyalkylene glycol component can be arbitrarily combined.

The content proportion of the polyalkylene glycol component in theliquid component is preferably greater than the content proportion ofthe first solvent in the liquid component. As a result, the firstsolvent is easily dissolved, and high dissociability of the solute inthe liquid component is easily secured, so that the film restorationeffect of the dielectric layer can be enhanced.

(Non-Aqueous Solvent)

The liquid component may include a non-aqueous solvent other than thefirst solvent and the polyalkylene glycol component. Examples of thenon-aqueous solvent include a sulfone compound, a lactone compound, acarbonate compound, and a polyhydric alcohol other than the glycerincomponent and the polyalkylene glycol component.

Examples of the sulfone compound include sulfolane, dimethyl sulfoxide,and diethyl sulfoxide. Examples of the lactone compound includeγ-butyrolactone and γ-valerolactone. Examples of the carbonate compoundinclude dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate,ethylene carbonate, propylene carbonate, and fluoroethylene carbonate.

Examples of the polyhydric alcohol include alkylene glycol (such asethylene glycol or propylene glycol), trimethylolpropane, and a sugaralcohol having four or more hydroxy groups or a derivative thereof. Asthe sugar alcohol, a sugar alcohol described as a polyhydric alcoholconstituting the polyalkylene glycol component can be referred to. Asthe derivative of the sugar alcohol, examples of derivatives of glycerincan be referred to.

The liquid component may include one or two or more kinds of non-aqueoussolvents.

From the viewpoint of easily obtaining the effect of the first solventand the polyalkylene glycol component and enhancing the effect ofsuppressing swelling of the sealing body due to the liquid component,the content proportion of such a non-aqueous solvent in the liquidcomponent is preferably 10 mass % or less, and more preferably 5 mass %or less or 1 mass % or less.

(Solute)

The liquid component may include a solute. Examples of the soluteinclude an acid component and a base component. The liquid componentpreferably includes at least an acid component. When a conductivepolymer component contains a dopant, the acid component in theelectrolytic solution suppresses the dedoping phenomenon of the dopantand stabilizes conductivity of each polymer component. Even when thedopant is dedoped from the conductive polymer component, the acidcomponent of the electrolytic solution is again doped at a site fromwhich the dopant have been dedoped, and thus low ESR is likely to bemaintained. The electrolytic solution may contain a base componenttogether with an acid component. At least a part of the acid componentis neutralized by the base component. This enables corrosion of anelectrode due to the acid component to be suppressed while the acidcomponent is increased in concentration.

Examples of the acid component include carboxylic acid,sulfur-containing acids (such as sulfuric acid and sulfonic acid),boron-containing acids (such as boric acid, halogenated boric acid (suchas tetrafluoroboric acid), or partial esters thereof),phosphorus-containing acids (phosphoric acid, halogenated phosphoricacid (such as hexafluorophosphoric acid), phosphonic acid, phosphinicacid, or partial esters thereof), nitric acid, and nitrous acid. As theacid component, a condensate of a carboxylic acid and an inorganic acid(such as boric acid or phosphoric acid) may be used. The liquidcomponent may include one or two or more kinds of acid components.

The acid component is preferably at least one of carboxylic acid,sulfonic acid, a condensate of carboxylic acid and an inorganic acid, orthe like. Examples of the sulfonic acid include aliphatic sulfonic acidhaving 1 to 30 carbon atoms and aromatic sulfonic acid having 6 to 30carbon numbers. Examples of the carboxylic acid include aliphaticcarboxylic acid and aromatic carboxylic acid. Among them, aromaticcarboxylic acid is relatively stable. A polycarboxylic acid having twoor more hydroxy groups is also preferred. Specifically, phthalic acid,pyromellitic acid, and the like may be used as the aromatic carboxylicacid. Of them, phthalic acid is preferred.

The condensate of carboxylic acid and an inorganic acid is preferably acondensate of carboxylic acid and a boric acid. Specifically, as such acondensate, borodisalicylic acid, borodiglycolic acid, borodioxalicacid, and the like may be used.

Examples of the base component include ammonia, amine (specifically,primary amine, secondary amine, or tertiary amine), a quaternaryammonium compound, and an amidinium compound. The liquid component mayinclude one or two or more kinds of base components.

The amine may be any of aliphatic, aromatic, and heterocyclic. Examplesof the amine include methyl amine, dimethyl amine, trimethyl amine,ethyl amine, diethyl amine, triethyl amine, ethylene diamine,N,N-diisopropylethyl amine, tetramethylethylene diamine, hexamethylenediamine, spermidine, spermine, amantadine, aniline, phenethylamine,toluidine, pyrrolidine, piperidine, piperazine, morpholine, imidazole,pyridine, pyridazine, pyrimidine, pyrazine, and 4-dimethylaminopyridine.Examples of the quaternary ammonium compound include amidine compounds(also including imidazole compounds).

The liquid component may include the acid component and the basecomponent in a free state or in a salt form, respectively. The liquidcomponent may include an organic salt. Examples of the organic saltinclude those in which at least one of the acid component and the basecomponent is organic. Examples of the organic salt includetrimethylamine maleate, triethylamine phthalate, ethyldimethylaminephthalate, mono 1,2,3,4-tetramethylimidazolinium phthalate, mono1,3-dimethyl-2 ethylimidazolinium phthalate, and triethylamineborodisalicylate.

The pH of the liquid component is preferably 4 or less, and may be 3.8or less or 3.6 or less. When the pH of the electrolytic solution is setin such a range, deterioration of the conductive polymer component iseasily suppressed. The pH is preferably 1.0 or more.

The concentration of the solute in the liquid component is, for example,0.1 mass % or more, and is preferably 0.5 mass % or more. When theconcentration of the solute is in such a range, by using the firstsolvent and the polyalkylene glycol component in combination, the solutecan be dissociated in the liquid component with high dissociability, andhigh film restoration properties of the dielectric layer can be secured.The concentration of the solute is preferably 25 mass % or less, andmore preferably 20 mass % or less or 15 mass % or less. When theconcentration of the solute is in such a range, dedoping of the dopantcan be suppressed. These lower and upper limit values of the range inthe concentration of the solute can be arbitrarily combined.

(Others)

The content proportion of water in the liquid component may be less than1.5 mass % or 1 mass % or less, is preferably less than 0.5 mass %, andmay be 0.1 mass % or less or 0.01 mass % or less. The first solventtends to have relatively low solubility to water, but when the firstsolvent is used in combination with the polyalkylene glycol component,the first solvent is easily dissolved in the polyalkylene glycolcomponent by heating even when the content proportion of water in theliquid component is small. Although the first solvent has highcrystallinity, crystallization of the first solvent is suppressed oncethe first solvent is dissolved in the polyalkylene glycol component. Thecontent proportion of water is a content proportion in the liquidcomponent of the electrolytic capacitor in the initial state.

Although the liquid component including the first solvent tends to havea relatively high viscosity at 20° C., the first solvent can bedissolved in the polyalkylene glycol component by heating when theliquid component is used in combination with the polyalkylene glycolcomponent. The viscosity at 20° C. of the liquid component is, forexample, 200 mPa·s or more, and may be 500 mPa·s or more. Even when theviscosity at 20° C. of the liquid component is in such a range, theviscosity can be reduced by heating. Hence, the conductive polymer ofthe capacitor element can be easily impregnated with the liquidcomponent, high film restoration properties of the dielectric layer iseasily secured, and high conductivity can be easily secured by theconductive polymer being oriented.

In the present specification, the viscosity of the liquid component canbe measured using a vibration type viscometer. As the vibration typeviscometer, for example, a vibration type viscometer VM-100Amanufactured by CBC Co., Ltd. is used.

(Capacitor Element)

The capacitor element includes at least an anode body that includes adielectric layer on a surface of the anode body and a conductive polymerthat covers a part of the dielectric layer.

(Anode Body)

The anode body may contain a valve metal, an alloy containing a valvemetal, a compound containing a valve metal, or the like. These materialscan be used singly or in combination of two or more kinds thereof. Asthe valve metal, for example, aluminum, tantalum, niobium, and titaniumare preferably used. The anode body having a porous surface can beobtained, for example, by roughening a surface of a base material (suchas a foil-shaped or plate-shaped base material) containing a valve metalby etching or the like. The anode body may be a molded body of particlesthat contain a valve metal or a sintered body of the molded body. Thesintered body has a porous structure.

(Dielectric Layer)

The dielectric layer is formed by anodizing the valve metal of thesurface of the anode body by an anodizing treatment or the like. It issufficient that the dielectric layer is formed so as to cover at least apart of the anode body. Usually, the dielectric layer is formed on thesurface of the anode body. Since the dielectric layer is formed on theporous surface of the anode body, the dielectric layer is formed alonginner wall surfaces of holes and hollows (pits) in the surface of theanode body.

The dielectric layer contains an oxide of a valve metal. For example,when tantalum is used as the valve metal, the dielectric layer containsTa₂O₅, and when aluminum is used as the valve metal, the dielectriclayer contains Al₂O₃. The dielectric layer is not limited thereto, andany dielectric layer may be used as long as the dielectric layerfunctions as a dielectric body. When a surface of the anode body isporous, the dielectric layer is formed along the surface of the anodebody (including inner wall faces of holes).

(Conductive Polymer Layer)

The conductive polymer is attached to cover a part of the dielectriclayer so as to form a conductive polymer layer. The conductive polymerconstitutes at least a part of the cathode body in the electrolyticcapacitor. The conductive polymer layer may further contain at least oneof a dopant and an additive, as necessary.

Examples of the conductive polymer include polypyrrole, polythiophene,polyfuran, polyaniline, polyacetylene, polyphenylene, polyphenylenevinylene, polyacene, and polythiophene vinylene. These may be usedsingly or in combination of two or more kinds thereof, or may be acopolymer of two or more kinds of monomers.

In the present specification, polypyrrole, polythiophene, polyfuran,polyaniline, and the like mean polymers having, as a basic skeleton,polypyrrole, polythiophene, polyfuran, polyaniline, and the like,respectively. Thus, polypyrrole, polythiophene, polyfuran, polyaniline,and the like each can also include its derivative. For example,polythiophene includes poly(3,4-ethylenedioxythiophene) and the like.

The dopant may be a polyanion. Specific examples of the polyanioninclude polyvinylsulfonic acid, polystyrenesulfonic acid,polyallylsulfonic acid, polyacrylsulfonic acid, polymethacrylsulfonicacid, poly(2-acrylamido-2-methylpropanesulfonic acid),polyisoprenesulfonic acid, and polyacrylic acid. These may be usedsingly or in combination of two or more kinds thereof. These may be apolymer of a single monomer or a copolymer of two or more kinds ofmonomers. Among them, a polyanion derived from polystyrenesulfonic acidis preferred.

The conductive polymer layer can be formed, for example, by chemicallyand/or electrolytically polymerizing a raw material monomer on thedielectric layer. Alternatively, the conductive polymer layer can beformed by bringing a solution in which the conductive polymer isdissolved or a dispersion liquid in which the conductive polymer isdispersed into contact with the dielectric layer. The conductive polymerlayer may be formed to cover at least a part of the dielectric layer.

A metal foil may also be used for the cathode body as well as the anodebody. The type of the metal is not particularly limited, but it ispreferable to use a valve metal such as aluminum, tantalum, or niobiumor an alloy containing the valve metal. A surface of the metal foil maybe roughened as necessary. On the surface of the metal foil, ananodization film, a film of a metal different from the metal thatconstitutes the metal foil (different type of metal), or a nonmetal filmmay be provided. Examples of the different type of metal and thenonmetal include metals such as titanium and nonmetals such as carbon.

(Separator)

When a metal foil is used for the cathode body, a separator may bedisposed between the metal foil and the anode body. The separator is notparticularly limited. For example, it is possible to use an unwovenfabric including fibers of cellulose, polyethylene terephthalate,vinylon, or polyamide (for example, aliphatic polyamide or aromaticpolyamide such as aramid).

(Others)

The electrolytic capacitor may be a wound type, or may be either a chiptype or a laminated type. The configuration of the capacitor element maybe selected in accordance with the type of the electrolytic capacitor.

(Container)

As a material for the container, for example, a metal such as aluminum,stainless steel, copper, iron, or brass, or an alloy thereof can beused. The shape of the container is not particularly limited as long asthe container can house the capacitor element and the liquid component.

(Sealing Body)

The sealing body is not particularly limited as long as the sealing bodyseals the opening of the container. The sealing body usually contains anelastic polymer. The sealing body may further contain a crosslinkingagent that crosslinks the elastic polymer, an additive, and the like.

As the elastic polymer, an insulating material is used. Examples of theelastic polymer include butyl rubber, isoprene rubber, silicone rubber,fluororubber, ethylene-propylene rubber, and chlorosulfonatedpolyethylene rubber (such as Hypalon™ rubber). The sealing body maycontain one or two or more kinds of elastic polymers.

Although the elastic polymer has high sealing properties, the elasticpolymer does not have sufficient heat resistance. That is, the elasticpolymer is oxidized and deteriorated in a high-temperature environmentto be brittle, and thus the sealing function of the sealing body isdeteriorated. The electrolytic capacitor is supposed to be used in ahigh-temperature environment such as in an engine room of a vehicle (anautomobile or the like) or near the engine room. In the electrolyticcapacitor including the liquid component, when the liquid component hashigh affinity for the elastic polymer, the elastic polymer is easilyswollen by the liquid component. The elastic polymer swollen by theliquid component is more easily deteriorated in a high-temperatureenvironment. According to the present disclosure, by using theabove-described liquid component, deterioration of the elastic polymercontained in the sealing body can be effectively suppressed, and anelectrolytic capacitor excellent in heat resistance is obtained.

The proportion of the elastic polymer in the sealing body is, forexample, 10 mass % or more, and may be 20 mass % or more. When theproportion of the elastic polymer is in such a range, the sealing bodyis likely to deteriorate in a high-temperature environment. Even in sucha case, deterioration of the elastic polymer can be suppressed by usingthe above-described liquid component, and high heat resistance of theelectrolytic capacitor can be secured. From the easily securing thestrength of the sealing body, the proportion of the elastic polymer ispreferably 50 mass % or less or 40 mass % or less. When the elasticpolymer is crosslinked with a crosslinking agent, the proportion of theelastic polymer is a proportion of the elastic polymer including thecrosslinking agent.

The elastic polymer constituting the sealing body is usually crosslinkedwith a crosslinking agent. In particular, an electrolytic capacitorincluding a sealing body that contains an elastic polymer crosslinkedwith at least one crosslinking agent selected from the group consistingof a phenolic resin (such as an alkylphenolic resin oligomer) and aperoxide (such as an organic peroxide) is suitable for use applicationsrequiring particularly high heat resistance. Even in the case of usingsuch a sealing body, when a conventional liquid component in the relatedart is used, deterioration of the sealing body cannot be suppressed dueto swelling of the liquid component in a high-temperature environment insome cases. According to the present disclosure, since theabove-described liquid component is used, even in the case of using sucha sealing body that is assumed to be used in a high-temperatureenvironment, deterioration of the sealing body can be suppressed, andhigh heat resistance can be secured.

The additive may include, for example, at least one selected from thegroup consisting of a reinforcing agent (carbon or the like such ascarbon black), an antioxidant, an antiaging agent, a crosslinking agent,a cross-linking promoter, a dispersion aid, a modifier, a vulcanizingagent, a vulcanization aid, and a processing aid.

The electrolytic capacitor has high heat resistance, and use of theelectrolytic capacitor can be ensured in a high-temperature environment.For example, use of the electrolytic capacitor can be ensured at atemperature of 120° C. (or 150° C.) for 2000 hours or longer. Theelectrolytic capacitor is also suitable for use applications in anengine room of a vehicle or in the vicinity thereof where highdurability and heat resistance are required.

The present disclosure also includes an electrolytic capacitor moduleincluding a plurality of the electrolytic capacitors as described above.The electrolytic capacitor module may include a plurality of theelectrolytic capacitors connected in parallel. When a current of 20 A ormore is applied to entire module of an electrolytic capacitor module inwhich a plurality of electrolytic capacitors in the related art areconnected in parallel, the temperature of each electrolytic capacitor isincreased to 100° C. or higher (sometimes, 120° C. or higher or 150° C.or higher) due to the ESR of each electrolytic capacitor, and thus theelectrolytic capacitor cannot be used. In some cases, a large current of50 A or more or 100 A or more may be applied to the entire module. Sincethe electrolytic capacitor of the present disclosure is excellent inheat resistance, a plurality of the electrolytic capacitors areconnected in parallel to constitute an electrolytic capacitor module, sothat use of the electrolytic capacitor can be ensured for a long periodof time (specifically, 1000 hours or longer, preferably 1500 hours orlonger, and more preferably 2000 hours or longer) even when a current of20 A or more (or 50 A or more or 100 A or more) is applied to the entiremodule. The allowable current of the entire electrolytic capacitormodule as described above may be 20 A or more, or may be 50 A or more or100 A or more.

FIG. 1 is a schematic cross-sectional view illustrating an electrolyticcapacitor according to the present exemplary embodiment, and FIG. 2 is aschematic view illustrating a partially developed capacitor element ofthe electrolytic capacitor.

The electrolytic capacitor includes, for example, capacitor element 10,bottomed case 101 that houses capacitor element 10 and a liquidcomponent (not illustrated), sealing body 102 that closes an opening ofbottomed case 101, seat plate 103 that covers sealing body 102, leadwires 104A, 104B led out from sealing body 102 and penetrating seatplate 103, and lead tabs 105A, 105B connecting the lead wires and theelectrodes of capacitor element 10. The vicinity of an opening end ofbottomed case 101 is drawn inward, and the opening end is curled toswage sealing body 102.

Capacitor element 10 is, for example, a wound body as illustrated inFIG. 2. The wound body includes anode body 11 connected to lead tab105A, cathode body 12 connected to lead tab 105B, and separator 13. Aconductive polymer layer (not illustrated) is formed on anode body 11.At least the conductive polymer layer of capacitor element 10 isimpregnated with the liquid component.

Anode body 11 and cathode body 12 are wound with separator 13 interposedbetween anode body 11 and cathode body 12. The outermost circumferenceof the wound body is fixed with winding stop tape 14. FIG. 2 illustratesa state in which a part of the wound body is developed before theoutermost circumference of the wound body is stopped.

The electrolytic capacitor may have at least one capacitor element, andmay have a plurality of capacitor elements. The number of capacitorelements included in the electrolytic capacitor may be determined inaccordance with use applications.

[Method for Manufacturing Electrolytic Capacitor]

The electrolytic capacitor is manufactured by a manufacturing methodincluding at least a step of preparing the above-described liquidcomponent, a conductive polymer impregnating step of impregnating adielectric layer with a conductive polymer, and a liquid componentimpregnating step of impregnating a capacitor element with the liquidcomponent after the conductive polymer impregnating step. The method formanufacturing an electrolytic capacitor may include a step of adjustingthe viscosity of the liquid component before the liquid componentimpregnating step. The method for manufacturing an electrolyticcapacitor may further include a step of preparing a capacitor elementand a step of sealing the capacitor element.

Hereinafter, an example of the method for manufacturing an electrolyticcapacitor will be described.

(1) Step of Preparing Capacitor Element 10 (i) Step of Preparing AnodeBody 11 Having Dielectric Layer and Cathode Body 12

A metal foil made of a valve metal is used as a raw material for anodebody 11 and cathode body 12. In the case of anode body 11, a surface ofthe metal foil is roughened by an etching process or the like, so that aplurality of recesses and projections are formed on the surface of themetal foil. Next, a dielectric layer is formed on the roughened surfaceof the metal foil by an anodizing treatment or the like. As necessary,the surface of cathode body 12 may be roughened.

(ii) Preparation of Wound Body

Anode body 11 and cathode body 12 are wound with separator 13 interposedbetween anode body 11 and cathode body 12 to prepare a wound body.Winding stop tape 14 is disposed on an outer surface of cathode body 12positioned on an outermost layer of the wound body to fix an end ofcathode body 12. As necessary, the anodizing treatment is furtherperformed on the wound body.

(iii) Step of Forming Capacitor Element 10

Capacitor element 10 can be formed by impregnating a dielectric layerwith a conductive polymer (conductive polymer impregnating step). Forexample, a dielectric layer is impregnated with a liquid of theconductive polymer dispersion so that a conductive polymer film isformed to cover at least a part of the dielectric layer. Consequently,capacitor element 10 in which the conductive polymer is disposed betweenanode body 11 and cathode body 12 is obtained. The step of applying thepolymer dispersion on the surface of the dielectric layer may berepeated two or more times.

The conductive polymer dispersion contains, for example, a conductivepolymer and a liquid medium in which the conductive polymer isdispersed. Examples of the liquid medium include water, an organicliquid medium, and a mixture thereof. The conductive polymer dispersionmay further contain at least one of a dopant and an additive, asnecessary. When the conductive polymer dispersion contains the firstsolvent, the dispersion hardly penetrates into the dielectric layer, andthe dielectric layer is hardly impregnated with the conductive polymer.Hence, it is preferable that the conductive polymer dispersion does notcontain the first solvent.

(2) Step of Preparing Liquid Component

The liquid component can be prepared by mixing constituents of theliquid component. Although the first solvent has low solubility to thenon-aqueous solvent, a liquid component in which the first solvent isuniformly dissolved can be prepared by using the first solvent incombination with the polyalkylene glycol component. This step may beperformed before the liquid component impregnating step, may beperformed before or after the preparation of the capacitor element, ormay be performed while the capacitor element is prepared.

More specifically, this step may include a step of dissolving the firstsolvent in the polyalkylene glycol component. When the first solvent andthe polyalkylene glycol component are heated to a temperature higherthan the melting point of these components and a temperature less thanor equal to the boiling point or decomposition temperature of thesecomponents, the first solvent can be dissolved in the polyalkyleneglycol component. When the liquid component includes other components(such as a solute and another non-aqueous solvent), the other componentsmay coexist at the stage of dissolving the first solvent. Once the firstsolvent is dissolved in the polyalkylene glycol component, the firstsolvent is hardly precipitated even when the first solvent is cooled.Thus, when the liquid component includes other components, the othercomponents can also be mixed after the first solvent is dissolved in thepolyalkylene glycol component by heating and then cooled.

The heating temperature ranges, for example, from 30° C. to 200° C.,inclusive, and may range from 50° C. to 100° C., inclusive.

(3) Step of Adjusting Viscosity of Liquid Component

The viscosity of the liquid component may be adjusted before the liquidcomponent impregnating step. The viscosity of the liquid component canbe adjusted, for example, by adjusting the temperature of the liquidcomponent. More specifically, the viscosity may be adjusted by heatingthe liquid component. This step may be performed in the step ofpreparing a liquid component. More specifically, a liquid component maybe prepared under heating, and capacitor element 10 may be impregnatedwith the liquid component in a state where the viscosity of the liquidcomponent is reduced.

Through this step, the viscosity of the liquid component to be subjectedto impregnation is set to preferably less than 200 mPa·s, and may be setto 100 mPa·s or less or 70 mPa·s or less. When the first solvent is usedin combination with the polyalkylene glycol component, the viscosity ofthe liquid component can be adjusted in such a range by heating. Thus,the conductive polymer of the capacitor element can be easilyimpregnated with the liquid component, high film restoration propertiesof the dielectric layer is easily secured, and high conductivity can beeasily secured by the conductive polymer being oriented.

The temperature of the liquid component to be subjected to impregnationmay range, for example, from 10° C. to 120° C., inclusive, or may rangefrom 20° C. to 100° C., inclusive or from 20° C. to 70° C., inclusive.By heating the liquid component, the temperature of the liquid componentto be subjected to impregnation may be adjusted to a temperature from50° C. to 120° C., inclusive, from 50° C. to 100° C., inclusive, or from50° C. to 70° C., inclusive.

(4) Liquid Component Impregnating Step

In this step, capacitor element 10 is impregnated with the liquidcomponent. It is thus possible to achieve an electrolytic capacitorincluding the conductive polymer and the liquid component. This step isperformed after the conductive polymer impregnating step. Capacitorelement 10 may be impregnated with the liquid component, for example, byhousing capacitor element 10 and the liquid component in the container,by immersing capacitor element 10 in the liquid component, or by addingthe liquid component dropwise to capacitor element 10.

(5) Step of Sealing Capacitor Element

Capacitor element 10 is housed in bottomed case 101 so that lead wires104A, 104B are positioned on an opening side of the bottomed case 101.The liquid component is also housed in bottomed case 101. Next, theopening of bottomed case 101 is closed by sealing body 102 through whichthe respective lead wires pass, an opening end of bottomed case 101 iscurled to swage sealing body 102, and seat plate 103 is disposed on acurled part. In this way, the electrolytic capacitor as illustrated inFIG. 1 is completed.

Although the winding-type electrolytic capacitor has been described inthe above exemplary embodiment, the scope of application of the presentdisclosure is not limited to the above. The present disclosure can alsobe applied to other electrolytic capacitors including, for example, achip-type electrolytic capacitor using a sintered metal body as an anodebody and a laminated-type electrolytic capacitor using a metal plate asan anode body.

Examples

Hereinafter, the present disclosure will be specifically described basedon Examples and Comparative Examples. However, the present disclosure isnot limited to the following Examples.

<<Production of Electrolytic Capacitors E1 to E16 and C1 to C4>>

A wound electrolytic capacitor (diameter of 10 mm×length (L) of 10 mm)having a rated voltage of 25 V and a rated capacitance of 330 g wasproduced. A specific method for manufacturing an electrolytic capacitorwill be described below.

(Preparation of Anode Body)

An aluminum foil having a thickness of 100 μm was subjected to anetching treatment to roughen the surface of the aluminum foil. Then, adielectric layer was formed on the surface of the aluminum foil by ananodizing treatment. The anodizing treatment was performed by immersingthe aluminum foil in an ammonium adipate solution and applying a voltageof 180 V to the aluminum foil. Then, the aluminum foil was cut toprepare an anode body.

(Preparation of Cathode Body)

An aluminum foil having a thickness of 50 μm was subjected to an etchingtreatment to roughen the surface of the aluminum foil. Then, thealuminum foil was cut to prepare a cathode body.

(Production of Wound Body)

An anode lead tab and a cathode lead tab were connected to the anodebody and the cathode body, respectively, and the anode body and thecathode body were wound with a separator interposed between the anodebody and the cathode body while the lead tabs were rolled in the anodebody, the cathode body, and the separator. An anode lead wire and acathode lead wire were connected to the ends of the lead tabs protrudingfrom the wound body, respectively. The produced wound body was subjectedto an anodizing treatment again to form a dielectric layer on thecutting end of the anode body. Next, the end of the outer surface of thewound body was fixed with a winding stop tape to produce a wound body.

(Preparation of Polymer Dispersion)

A mixed solution was prepared by dissolving, in ion-exchanged water,3,4-ethylenedioxythiophene and polystyrene sulfonic acid (PSS, weightaverage molecular weight: 100000) that is a polymer dopant. While themixed solution was being stirred, iron(III) sulfate (oxidant) dissolvedin ion-exchanged water was added to perform a polymerization reaction.After the reaction, the obtained reaction solution was dialyzed toremove the unreacted monomer and excess oxidant, so that a polymerdispersion containing polyethylene dioxythiophene doped with about 5mass % of PSS (PEDOT/PSS) was obtained.

(Formation of Solid Electrolyte Layer)

The wound body was immersed in the polymer dispersion housed in apredetermined container for 5 minutes in a reduced pressure atmosphere(40 kPa), and then the wound body was pulled out from the polymerdispersion. Next, the wound body impregnated with the polymer dispersionwas dried in a drying furnace at 150° C. for 20 minutes to form a solidelectrolyte layer made of a conductive polymer layer covering at least apart of the dielectric layer. In this way, a capacitor element wasformed.

(Preparation of Liquid Component)

The first solvent shown in Table 1 and the polyalkylene glycol componentwere mixed, and the mixture was heated to 95° C. under stirring todissolve the first solvent. To the obtained mixed solvent, triethylaminephthalate was added and mixed as the solute to have a concentration of15 mass %. In this way, a liquid component was prepared. The SP value ofglycerin was 16.5, and the SP values of diglycerin and polyglycerin were16 or more.

In electrolytic capacitors C1 to C4, non-aqueous solvents shown in Table1 were used as the liquid component.

(Assembling of Electrolytic Capacitor)

The liquid component was heated to 60° C. or higher to adjust theviscosity to less than 200 mPa·s. In a case, 200 mg of the liquidcomponent with the adjusted viscosity was housed together with thecapacitor element, and the capacitor element was impregnated with theliquid component in a reduced pressure atmosphere (40 kPa) over 5minutes. The opening of the case was sealed using the sealing body tocomplete an electrolytic capacitor as illustrated in FIG. 1. Then, anaging treatment was performed at 130° C. for 2 hours while a ratedvoltage was being applied. The viscosity of the liquid component wasmeasured using a vibration type viscometer VM-100A manufactured by CBCCo., Ltd.

As the sealing body, a disk-shaped elastic member containing butylrubber obtained by kneading a butyl polymer, a peroxide-basedcrosslinking agent, an additive and molding these materials using a moldwas used. As the additive, a reinforcing agent (carbon black), across-linking promoter, a dispersion aid (stearic acid), a hinderedphenol-based antiaging agent, and a modifier (silane coupling agent)were used. The amount of each component used was adjusted so that thecontent of butyl rubber as the elastic polymer component in the sealingbody was the value in Table 1.

[Evaluation 1] (Measurement of ESR and Residual Amount of LiquidComponent)

The ESR (initial ESR) at a frequency of 100 kHz/Ω of the obtainedelectrolytic capacitor was measured using an LCR meter. To evaluatelong-term reliability, each of the resultant electrolytic capacitors washeld at 145° C. for 2000 hours while applying the rated voltage to eachof the resultant electrolytic capacitors. An increase rate of ESR (ΔESR)was then checked. ΔESR was represented by the ratio (Z/Z₀×100%) ofESR(Z) of the electrolytic capacitor after retention at 145° C. to theinitial value (Z₀). ESR(Z) was measured in the same manner as in theinitial ESR using the electrolytic capacitor after retention at 145° C.

The electrolytic capacitor after the ratio of increase in ESR wasconfirmed was decomposed, and the liquid component was recovered todetermine the mass (g). The residual amount of the liquid component wasrepresented by the ratio (m/m₀×100%) of the mass (m) of the liquidcomponent after retention at 145° C. to the initial mass (m₀) of theliquid component.

The evaluation results are shown in Table 1.

TABLE 1 Sealing Evaluation Liquid component body Residual Non-aqueousContent of ESR ESR ratio of First solvent PAG component solvent elasticinitial change liquid Content Content Content polymer value ratiocomponent Type (mass %) PAG Mw (mass %) Type (mass %) (mass %) (mΩ) (%)(%) E1 Glycerin 10 PEG 300 90 — 0 30 17 44 93 E2 Glycerin 30 PEG 300 70— 0 30 14 35 93 E3 Glycerin 70 PEG 300 30 — 0 30 12 33 95 E4 Glycerin 30PEG 300 50 EG 20 30 13 39 86 E5 Glycerin 30 PEG 300 50 SL 20 30 15 46 80E6 Glycerin 30 PEG 200 70 — 0 30 14 36 94 E7 Glycerin 30 PEG 600 70 — 030 14 36 95 E8 Glycerin 30 PEG 2000 70 — 0 30 15 35 95 E9 Glycerin 30PPG 400 70 — 0 30 14 39 92 E10 Glycerin 30 PPG 1000 70 — 0 30 16 40 93E11 Diglycerin 30 PEG 300 70 — 0 30 18 36 94 E12 Polyglycerin 310 30 PEG300 70 — 0 30 19 36 94 E13 Polyglycerin 750 30 PEG 300 70 — 0 30 21 3795 E14 Glycerin 30 PEG 300 70 — 0 10 14 34 95 E15 Glycerin 30 PEG 300 70— 0 30 14 35 93 E16 Glycerin 30 PEG 300 70 — 0 50 14 38 90 C1 — 0 — — 0GBL 100 30 12 345 42 C2 — 0 — — 0 EG 100 30 10 210 56 C3 — 0 — — 0 GBL100 50 12 443 35 C4 — 0 — — 0 EG 100 50 10 307 44 Polyglycerin 310:polyglycerin having a number average molecular weight of about 310Polyglycerin 750: polyglycerin having a number average molecular weightof about 750 PAG: polyalkylene glycol PEG: polyethylene glycol PPG:polypropylene glycol GBL: γ-butyrolactone EG: ethylene glycol SL:sulfolane

The electrolytic capacitor of the present disclosure can be used as ahybrid electrolytic capacitor. The electrolytic capacitor isparticularly suitable for use applications requiring high heatresistance. However, the use application of the electrolytic capacitoris not limited to these use applications.

What is claimed is:
 1. An electrolytic capacitor comprising: a capacitorelement; and a liquid component, wherein: the capacitor element includesan anode body that includes a dielectric layer on a surface of the anodebody, and a conductive polymer that covers a part of the dielectriclayer, the liquid component includes a first solvent and a polyalkyleneglycol component, and the first solvent contains at least a glycerincomponent.
 2. The electrolytic capacitor according to claim 1, wherein acontent proportion of the glycerin component in the liquid componentranges from 10 mass % to 70 mass %, inclusive.
 3. The electrolyticcapacitor according to claim 1, wherein a content proportion of thepolyalkylene glycol component in the liquid component is greater than acontent proportion of the glycerin component.
 4. The electrolyticcapacitor according to claim 1, wherein the glycerin component includesat least one selected from the group consisting of glycerin and aderivative of the glycerin.
 5. The electrolytic capacitor according toclaim 1, wherein the glycerin component includes at least one selectedfrom the group consisting of polyglycerin and a derivative of thepolyglycerin, and a number of repetitions of glycerin units in thepolyglycerin ranges from 2 to 12, inclusive.
 6. An electrolyticcapacitor comprising: a capacitor element; and a liquid component,wherein: the capacitor element includes an anode body that includes adielectric layer on a surface of the anode body, a cathode body, and aconductive polymer that is disposed between the anode body and thecathode body, the liquid component includes a first solvent and apolyalkylene glycol component, and a solubility parameter of the firstsolvent is 15 (cal/cm³)^(1/2) or more.
 7. The electrolytic capacitoraccording to claim 6, wherein a content proportion of the first solventin the liquid component ranges from 10 mass % to 70 mass %, inclusive.8. The electrolytic capacitor according to claim 6, wherein a contentproportion of the polyalkylene glycol component in the liquid componentis greater than a content proportion of the first solvent in the liquidcomponent.
 9. The electrolytic capacitor according to claim 1, wherein acontent proportion of the polyalkylene glycol component in the liquidcomponent ranges from 30 mass % to 95 mass %, inclusive.
 10. Theelectrolytic capacitor according to claim 1, wherein a weight averagemolecular weight of the polyalkylene glycol component ranges from 200 to2000, inclusive.
 11. The electrolytic capacitor according to claim 1,wherein the liquid component includes a solute at a proportion of 0.5mass % or more.
 12. The electrolytic capacitor according to claim 1,wherein the liquid component has a viscosity at 20° C. of 200 mPa·s ormore.
 13. The electrolytic capacitor according to claim 1, furthercomprising: a container housing the capacitor element and the liquidcomponent, a container having an opening; and a sealing body that sealsthe opening, wherein: the sealing body contains an elastic polymer, anda proportion of the elastic polymer in the sealing body is 10 mass % ormore.
 14. The electrolytic capacitor according to claim 13, wherein theelastic polymer is crosslinked with at least one crosslinking agentselected from the group consisting of a phenolic resin and a peroxide.15. The electrolytic capacitor according to claim 1, wherein use of theelectrolytic capacitor is ensured at a temperature of 120° C. for 2000hours or longer.
 16. An electrolytic capacitor module comprising aplurality of electrolytic capacitors which are connected in parallel,the plurality of electrolytic capacitors including the electrolyticcapacitor according to claim
 1. 17. The electrolytic capacitor moduleaccording to claim 16, wherein an allowable current of the electrolyticcapacitor module is 20 A or more.
 18. A method for manufacturing anelectrolytic capacitor, the electrolytic capacitor including a capacitorelement and a liquid component, the capacitor element including an anodebody including (i) a dielectric layer on a surface of the anode body and(ii) a conductive polymer covering a part of the dielectric layer, themethod comprising: a step of preparing a liquid component that includesa first solvent containing at least a glycerin component, and apolyalkylene glycol component; a conductive polymer impregnating step ofimpregnating the dielectric layer with the conductive polymer; and aliquid component impregnating step of impregnating the capacitor elementwith the liquid component after the conductive polymer impregnatingstep.
 19. A method for manufacturing an electrolytic capacitor, theelectrolytic capacitor including a capacitor element and a liquidcomponent, the capacitor element including an anode body including (i) adielectric layer on a surface of the anode body and (ii) a conductivepolymer covering a part of the dielectric layer, the method comprising:a step of preparing a liquid component that includes a first solventhaving a solubility parameter of 15 (cal/cm³)^(1/2) or more, and apolyalkylene glycol component; a conductive polymer impregnating step ofimpregnating the dielectric layer with the conductive polymer; and aliquid component impregnating step of impregnating the capacitor elementwith the liquid component after the conductive polymer impregnatingstep.
 20. The method for manufacturing the electrolytic capacitoraccording to claim 18, wherein the step of preparing the liquidcomponent includes a step of dissolving the first solvent in thepolyalkylene glycol component.
 21. The method for manufacturing theelectrolytic capacitor according to claim 18, further comprising a stepof adjusting a viscosity of the liquid component to be less than 200mPa·s before the liquid component impregnating step.